S-7760A Datasheet, PDF (11/53 Pages) Seiko Instruments Inc – PROGRAMMABLE PORT CONTROLLER (PORT EXPANDER WITH BUILT-IN E2PROM CIRCUIT)

PROGRAMMABLE PORT CONTROLLER (PORT EXPANDER WITH BUILT-IN E²PROM CIRCUIT)
Rev.1.3_00
S-7760A
„ Device Addressing
To start communication, the master device (MPU) on the system generates a start condition for the slave device
(S-7760A). After that, the master device sends a device address with 7-bit length and Read/Write instruction code with
1-bit length on the SDA bus. The higher 3 bits in a device address (DC2, DC1, DC0) are device codes. A device code can
obtain the fixed value selected by option. Command is omitted if a device code does not correspond. Set the command in
the following 4 bits (C3, C2, C1, C0). Next, by selecting either of Read or Write by Read/Write bit, the S-7760A sends an
acknowledgement signal back. If the second byte is Read, MPU sends an acknowledgement signal back after outputting
data Read with 8-bit length. If it is Write, after outputting Write data with 8-bit length, the S-7760A sends an
acknowledgement signal back. To finish these sequential commands, the S-7760A generates a stop condition as its final
procedure.
There is a 1-byte command for the S-7760A, but inputting the second byte as a dummy does not affect on this device
addressing. In this case, the operation for the second byte is as well as for Read/Write because of the bit corresponding to
Read/Write in the first byte.
Start
Device
Code
Read/Write bit ^{Acknowledgment}
Signal
Command
STA DC2 DC1 DC0 C3
C2
C1
MSB
Register data
C0 R / W ACK
LSB
Stop
B7
B6
B5
B4
B3
B2
B1
B0 ACK STP
MSB
LSB
Figure 13 Device Address
Seiko Instruments Inc.
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